Fuel issue

I have a 2000 sivlerado 1500 5.3. I have 126000 on it. I have noticed over the last couple weeks when I get in the high rpms the truck hesitates a little like its not getting enough fuel. When I punch it from a dead stop it lacks power at first. Also if the truck sits for around 12 hours and I start it up it acts like its not getting enough fuel at first. Any ideas any known issues? I have already done a tune up and changed the fuel filter 2 months ago. Thank you.